Ulster will play host to the Scarlets in their RaboDirect PRO12 semi-final after coming from behind to defeat Cardiff Blues 37-13 at Ravenhill.
Tries from Ruan Pienaar and Robbie Diack, along with a brace by Andrew Trimble, helped a workmanlike Ulster achieve the home semi-final.
This was a fragmented and disjointed encounter, but it will matter little to the Irish side, who have led the league for the majority of this campaign.
A scrappy and uninspiring win it may have been, but the performance was testament to the tenacity and efficiency of the men in white. Ulster, who led throughout the evening, thoroughly deserved their win, but a resilient and physical Cardiff frustrated them every step of the way.
The game got off to an industrious start, with Ulster driving energetically at the Cardiff defence. Even incoming Lions looked jittery, however, as Tommy Bowe dropped a routine ball early on.
Ulster were caught napping on the four minute mark, when centre Dafydd Hewitt sauntered unopposed through the home defence. Rhys Patchell converted to give the visitors a seven-point lead.
Ulster responded in the correct fashion, and a powerful scrum earned them a deserved penalty on six minutes. Pienaar missed the resulting kick, however.
The South African playmaker made amends two minutes later, seizing upon a calamitous error in the Blues' defence to score under the posts. He subsequently converted his effort to make it 7-7.
Ulster seemed to have regained the momentum after a nervy start, but a succession of handling errors undid their hard work. A sublime kick by Pienaar on thirteen minutes encamped the hosts in the Blues' corner to set up perfect field-position. From the ensuing lineout, Ulster failed to control possession, however.
Cardiff were beginning to accumulate some decent possession, and an Ulster infringement saw Patchell restore the Blues' lead on 20 minutes to make it 7-10.
Pienaar secured parity for the league leaders on 25 minutes, following a high tackle on replacement prop Declan Fitzpatrick.
The impressive Patchell regained his side's lead on 27 minutes with a wonderful drop-goal from a good 30 metres to make it 10-13 in favour of the Welshmen.
Cardiff continued their recovery from a sluggish start, and were assisted by a string of Ulster mistakes. The hosts should have secured a penalty shortly thereafter, when Bowe seemed to be taken out with the line at his mercy. But referee Paterson waved play on.
Ulster made a creditable start to the second period, with Nick Williams and his back row colleagues battering the Cardiff defence. Their improvement earned its reward on 42 minutes, when Trimble barged over for a try in the corner. Piennaar converted to make it 17-13 to the Ulstermen.
Pienaar extended the lead even further a minute later, with a well-taken penalty from just inside his own half. Ulster's talisman extended the advantage on 49 minutes to earn his side a deserved ten-point cushion.
Ulster's intensity had increased markedly from an inconsistent first half effort. Cardiff, despite their best efforts, appeared unable to respond.
Trimble scored again on 52 minutes, after winning a foot race with the Cardiff cover. Pienaar converted to make it 30-13. The introduction of Paddy Jackson for the second half aided the crispness of Ulster's midfield passing.
Ulster were now dominating territory and possession, through the deft kicking of Jackson and Pienaar.
The inevitable raft of substitutions, combined with the dreadful weather, disrupted the fluidity of the game, but if truth were told, Ulster were very much in the ascendancy by the final quarter of the match.
Robbie Diack completed the rout on 77 minutes when he crashed over from close range. Cardiff's defence, meanwhile, was not assisted by the sin binning of Hewitt for a rather cynical intervention.
Despite numerous opportunities, Ulster were unable to increase the winning margin, however.
For Cardiff, the loss punctuates a disappointing season for the club, and the Welsh regions in general. For Ulster, on the other hand, this emphatic win guarantees the home semi-final.
Tries: Pienaar, Trimble 2, Diack
Con: Pienaar 4
Pen: Pienaar 3
For Cardiff Blues:
Ulster: 15 Jared Payne, 14 Andrew Trimble, 13 Darren Cave, 12 Stuart Olding, 11 Tommy Bowe, 10 Ruan Pienaar, 9 Paul Marshall, 8 Nick Williams, 7 Chris Henry, 6 Robbie Diack, 5 Iain Henderson, 4 Johann Muller, 3 John Afoa, 2 Rory Best, 1 Callum Black.
Replacements: 16 Nigel Brady, 17 Tom Court, 18 Declan Fitzpatrick, 19 Dan Tuohy, 20 Sean Doyle, 21 Paddy Jackson, 22 Michael Allen, 23 Peter Nelson.
Cardiff Blues: 15 Dan Fish, 14 Alex Cuthbert, 13 Gavin Evans (c), 12 Dafydd Hewitt, 11 Harry Robinson, 10 Rhys Patchell, 9 Lewis Jones, 8 Michael Paterson, 7 Josh Navidi, 6 Luke Hamilton, 5 Lou Reed, 4 Bradley Davies, 3 Scott Andrews, 2 Kristian Dacey, 1 Taufa'ao Filise.
Replacements: 16 Marc Breeze, 17 Thomas Davies, 18 Campese Ma'afu, 19 Teofilo Paulo, 20 Macauley Cook, 21 Liam Davies, 22 Ceri Sweeney, 23 Tom James.
Referee: Neil Paterson (Scotland)
Assistant referees: Sean Gallagher (Ireland), Nigel Correll (Ireland)
Television match official: Simon McDowell (Ireland)
Citing Commissioner: Peter Ferguson (Ireland)
By Rory McGimpsey at Ravenhill